"What is the model of the phone? Some of them have OTG capability, just providing power for connected device is disabled by default. I had Samsung Galaxy S III Neo, power could be enabled with one command executed as super user. What do you need to…"

Here is a simple Android app for testing cheap Chinese USC-16 servo controller: USC-16 Demo User can select one of four servos, movement speed, and position. The app can also be used to communicate with other devices based on CH340 chip. Your Android version must be 4.1 or above and the device must have USB OTG feature.See More

Marek Suma's Blog

Here is a simple Android app for testing cheap Chinese USC-16 servo controller:USC-16 Demo User can select one of four servos, movement speed, and position. The app can also be used to communicate with other…